Brief_History_Computing

A Brief History of Computers Introduction to Computer Technology

Introduction The development of modern computer technology has been made possible by Human Nature Technological Advances Theoretical Advances This presentation takes a brief look at the human journey from prehistory to today with the focus on the development of the theory and practise of computing

Natural Patterns & Counting People notice patterns : this is how we learn from infancy. The first primitive counting mechanisms were developed to keep track of and predict seasons etc using the patterns observed in movement of the Sun, Moon, Stars etc Early counting devices included notches on sticks, knots in string and marks on walls.

Magic & Counting The ability to accurately predict natural events was a source of power in early human society People who could do so would strengthen their claim to supernatural privilege and/or power Record keeping was needed to help in accurate predictions and transmission of knowledge. Markings on antlers and bones indicate that people made notations of the phases of the moon as long as 30,000 years ago and suggest that the cave rituals and other cultural practices had a seasonal or periodical orientation.

Monumental Calendars The monumental structure, Stonehenge, was built in prehistoric England about 2800 BCE, Stonehenge is oriented towards equinoxes, solstices and lunar eclipses during the equinox This suggests usage as a complex permanent calendar. Stonehenge is just one of many similar monuments.

Early Counting Devices 6000 B.C. [ca]: Ishango bone type of tally stick in use 40001200 B.C.: Inhabitants of the first known civilization in Sumer keep records of commercial transactions on clay tablets These tablets are more than 4500 years old, from the dawn of civilised urban existence and they deal with accounts and tax records! (Taxes and death are always with us)

Towards Mechanising calculations: The Abacus The Abacus are the earliest known counting/calculation instruments. Used to aid mental calculations 3000 BCE: The abacus is invented in Babylonia Used by Greeks and Romans Refined to suit counting system of each culture Abacus were also developed by Native American cultures

Towards Mechanising calculations: Chinese Abacus Chinese used and refined abacus technology over a long period Chinese abacus (or suanpan): very efficient suanpan techniques have been developed to do multiplication, division, addition, subtraction, square root and cube root operations at high speed.

The Hindu Zero and Place Value The Hindu civilisation of India was alone among the ancients in developing a usable representation for numbers (about 2000 years ago) They also developed the concept of ZERO and with it the idea of place value. This enabled them to develop a high degree of skill in algebra. These concepts are critical to the binary system used in modern computers

What is a “Computer”? Origins of the word ‘computer’ 1646; applied to people whose job involved calculating (computing). These people generated highly accurate logarithmic tables, trigonometric tables, actuarial tables for insurance companies, gunnery tables for the army and navy, tables to predict the tides, the movement of the planets, all without the aid of any significant mechanical device. Modern Definition of a Computer A computer is an automatic electronic abacus. Some early computers used ten switching elements per numeral, but a modern computer is a binary abacus.

Towards Mechanising calculations: Other aids to calculation Logarithms (Logarithmic Tables) Date from the 16th century John Napier, invented and publicized a system of "logarithms" which allowed multiplication and division to be reduced to addition and subtraction . Napier’s Bones represent an application of the old Arabic lattice method of multiplication. The bones consist of a series of numbered rods, each inscribed with a multiplication table. The rods were usually made of ivory or bone, hence the name. Slide Rule: in 1621, an English mathematician and clergyman called William Oughtred used Napier's logarithms as the basis for the slide rule This remained an important tool in complex mathematical calculation until the invention of the computer.

Towards computers: The First Mechanical Calculator None of the devices we have so far looked at are true mechanical calculators…. [ They are really just tools that assist in calculation]

Towards computers: The First Mechanical Calculator The Forefathers of the Modern Computer Blaise Pascal (1623-1662) Gottfried Wilhelm von Leibniz (1646-1716) Charles Babbage (1812-1833)

Pascal’s Arithmetic Machine Pascal's Arithmetic Machine used a series of gears each with ten teeth. Numbers could be entered and the gear would turn the correct number of teeth. The gear train then supplied a mechanical answer equivalent to the correct arithmetic answer. The machine could only add and subtract, while multiplication and division operations were implemented by performing a series of additions or subtractions. NOTE: In fact the Arithmetic Machine could really only add, because subtractions were performed using complement techniques, in which the number to be subtracted is first converted into its complement, which is then added to the first number. Interestingly enough, modern computers employ similar complement techniques. [Known as 2’s complement mathematics] This gear train system is still used by mechanical odometers

Leibniz’s Step Reckoner Leibniz developed Pascal's ideas and, in 1671, introduced the Step Reckoner , a device which, as well as performing additions and subtractions, could multiply, divide, and evaluate square roots by series of stepped additions. Pascal's and Leibniz's devices were the forebears of today's desk-top computers, and derivations of these machines continued to be produced until their electronic equivalents finally became readily available and affordable in the early 1970s. Leibniz also strongly advocated the use of the binary number system , which is fundamental to the operation of modern computers .

Charles Babbage Difference Engine & Analytical Engine In 1822, Babbage proposed building a machine called the Difference Engine to automatically calculate mathematical tables. The Difference Engine was only partially completed when Babbage conceived the idea of another, more sophisticated machine called an Analytical Engine. The Analytical Engine was intended to use loops of Jacquard's punched cards to control an automatic calculator, which could make decisions based on the results of previous computations. The Analytical Machine was designed to be stream -driven and fully automatic rather than requiring the user to mechanically input all the data as did the Difference Engine. Neither machine was finished because Babbage kept updating his design.

Babbage’s Conditional Decisions The Analytical Machine was also intended to employ several features subsequently used in modern computers, including sequential control, branching, and looping. The conditional decision meant that the path a calculation would follow could be altered depending on the answer to the previous step in the calculation. The use of a card system to ‘store’ a program and the development of the conditional state were significant contributions to the future of computing Augusta Ada Lovelace (Lord Byron’s daughter) worked with Babbage and created a program for the Analytical Machine. She is considered to be the first programmer

Herman Hollerith’s Tabulating Machine The US government faced a dilemma because using the existing system collating census data by making tally marks in small squares on rolls of paper and then adding the marks together by hand was extremely time consuming. If the system remained unchanged, the data from the 1890 census would not be collated into any useful form until well after the 1900 census. During the 1880s Herman Hollerith, an American inventor decided to use Jacquard's punched cards to represent the census data, and to then read and collate this data using an automatic machine. (Apparently, he did not get this idea from Babbage.) Hollerith's final system included an automatic electrical tabulating machine with a large number of clock-like counters that accumulated the results. Operators could instruct the machine to examine each card for certain characteristics, such as profession, marital status, number of children, and so on.

The Birth of IBM (International Business Machines) Hollerith’s system proved to be both useful and efficient It was only useful for tabulation not for direct complex computation. Not a ‘real’ computer The use of perforated or punched cards for data entry was a major useful innovation In February 1924, Hollerith's company changed its name to International Business Machines , or IBM .

Punched Cards & Tape The original cards had round holes (45 per row by 1900). The use of punched cards (and paper tape) for computer input lasted for many years Later cards (about 1929 onwards) used rectangular cards and had 80 holes per row. (This is the type of computer card you may have seen since they were around for a long time.)

The First Programmable Computer Konrad Zuse (a German) built his first computer in 1938 The Z1 is today considered to be the first freely programmable computer of the world. In 1941 the Z3 (an improvement on Z1) was released. It was fully programmable and able to solve complex engineering equations. The Z3 was the first machine designed to work on the binary system. Perforated, discarded movie film was used for input.

WWII - Reading Enemy Secrets Colossus developed by British Military Intelligence to assist in code breaking First digital, electronic, programmable computer 1500 electronic valves (vacuum tubes) Kept secret for 50 years

WWII - ENIAC Was developed by [USA] Army Ordnance to compute World War II ballistic firing tables. Early electronic digital computer 1,800 Vacuum tubes ENIAC could discriminate the sign of a number, compare quantities for equality, add, subtract, multiply, divide, and extract square roots. ENIAC stored a maximum of twenty 10-digit decimal numbers.

Harvard Mark I Officially known as the IBM automatic sequence controlled calculator (ASCC) Brainchild of Howard H. Aiken The Mark I was constructed out of switches, relays, rotating shafts, and clutches, and was described as sounding like a "roomful of ladies knitting." The machine contained more than 750,000 components, was 50 feet long, 8 feet tall, and weighed approximately 5 tons! Instructions were read in on paper tape, data was provided on punched cards, and the device could only perform operations in the sequence in which they were received.

Digital Computer Basics Digital computers are essentially formed by connecting a lot of switches together. Each switch can be considered to be ON or OFF. The ON/OFF state of the switches can be modified as required, Combinations of switches can be used to implement primitive logical functions, which can in turn be used to realize more complex logical functions Advances in technology have lead to significant reductions in the size of modern computers and significant increases in their processing speed and memory capacity Moore’s Law: Moore predicted that the number of transistors per square inch on integrated circuits would double every 18 months. Most experts expect Moore's Law to hold for at least another two decades.

Developing Computer Technology Crucial Inventions Mechanical Computers Gears & Gear Train Punched Cards/Tape Relay Switches Electronic Computers Vacuum Tubes Transistors (1947) Integrated Circuits (1958) Microprocessors

Developing Computer Technology Important Ideas Zero Place Value Logic : Euler ; George Boole ; Augustus De Morgan; John Venn etc (Conditional reasoning and set theory) Binary Numbers The Turing Machine : Alan Turing: Description of hypothetical machine Von Neumann Machine : John von Neumann: Description of possible fixed structure for flexible (programmable) machine

Developing Computer Technology Important Ideas Programming Languages : Grace Hopper: Proposed that computers could be ’taught’ to read English. Her best-known contribution to computing was the invention of the compiler, the intermediate program that translates English language instructions into the language of the target computer. Teaching computers to ‘read’ natural language remains the goal of those who design computer languages and create various programming environments.

1973 AD to 1981 AD The First Personal Computers (PCs) IBM Acorn released PC in 1981 284-AT in 1984 Other The Altair 8800 (MITS became Microsoft) in 1975 TRS-80 (Radio Shack) 1977 Commodore PET 1980 Osborne I in 1981 Apple Apple II in 1977 Apple III in 1980 Lisa in 1983 First computer with mouse and graphical user interface before this computers used command line (typed text) input Macintosh in 1984

Email, Internet & WWW Since 1984 bigger, better, faster and ever cheaper computers that are easier to use and increasingly available to all. Development of Internet & Web technologies Almost instantaneous communication between computers Readily accessible stores of online documents

CP1030 Introduction to Information Technology Lectures for this subject contain an introduction to the current state of Information Communication Technologies (also known as ICTs) Topics covered include Hardware, Software (Application, OS & Utility), Input & Output, Storage, Communications & Networks, Enterprise Issues & Social Issues Security Practicals for this subject cover a number of contemporary software applications and aspects of these will also be covered in lectures.

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